The long-term goal of this research is to make available to the chemical community methods for the estimation of toxicity endpoints, especially carcinogenicity. Several aims are included in the research under this grant: (1) Enhancement of the carcinogenicity data base; (2) Development of a global carcinogenicity equation: (3) Further refinement of the NCI/NTP assay-based carcinogenicity equation developed during Phase 1; (4) Development of sex/species-specific carcinogenicity equstions for heterogeneous as well as more closely related sets of chemicals; (5) Development of organ-specific oncogenicity equations for 10 organ systems or sites; (6) Development of equations for carcinogenic potency for heterogeneous and more closely related data sets; (7) Development of carcinogenicity equations for closely related series of chemicals based on NCI/NTP, pharmaceutical, and CFR 21 data. The independent parameters will include physico-chemical parameters such as log P, molar refractivity, and molecular area and volume. Other parame- ters will include molecular connectivity indexes and MOLSTAC@ substructural descriptors. Statistical methodology will be based on discriminant analysis, multiple, partial and ridge regression. and principal component analysis.